Get-ChildItem -Path 'c:\Users\we_unite\Desktop\buy-market\group-buy-market' -Filter *.java -Recurse | ForEach-Object {
    $content = Get-Content $_.FullName -Raw
    $newContent = $content -replace '@we_unite', 'we_unite'
    Set-Content -Path $_.FullName -Value $newContent
}